Electric switch



Feb. 18, 1941. H. "r. OLSON ELECTRIC SWITCH Filed Oct. 7, 1937 2Sheets-Sheet 1 Ha T'Old 1: Olson Feb. 18, 1941. H. T. OLSON ELECTRICSWITCH Filed Oct. '7, 1937 2 Sheets-Sheet 2 jvwemwu Harold T. Ola'on/Patented Feb. 18, 1941 UNITED STATES PATENT OFFICE ruao'rmc swrronApplication October 7, 1937, Serial No. 167,754 12 Claims. (or. 200-152)The present invention relates to liquid flow switches, and f moreparticularly to mercury switches.

Mercury switches of the most common type 13 consist of a straighttubular glass envelope, in one end of which a pair of electrodes arelocated. A globule of mercury lies within the envelope and completes theelectrical circuit by bridging the electrodes when the envelope istipped so that 110 the electrode end is the loweri When the device bywhich the switch is actuated tips it past its horizontal position ratherrapidly, this construe tlon works out well for the reason that themercury then moves into or out of engagement with the electrodes ratherrapidly. The speed with which the mercury moves within the en velope ofsuch a switch depends on how rapidly the switch is tipped since theforce of gravity attempts to keep the mercury in the lowest por tion ofthe envelope and rapid movement of the envelope past its horizontalposition results in rapid movement of the mercury from one end of theenvelope to the other.

When an electrical circuit is made or broken between two conductors,there is a tendency i'or an arc to i'orm between the conductors at thetime they are close to each other. Arcing in a mercury switch shortensits life due to the ln= m tense heat oi. the arc which is destructive tothe electrodes and envelope loy arcing also contaminate the mercuryrendering it sluggish and eventually the mercury may become so contominateol and viscous that the useess of the switch is brought on end,It is therefore desirable to through this period of prox= unity or theconductors so quickly us possible. An object of invention is to provideo mercury switch in which the circuit is both music and broken with osnap notion to obviate the shove ololections.

Another object oi the invention is to indent the materiel tor-mint; theenvelope or. container oi mercury switch either lroin the outside orlrorn the inside and thereby provide an obstacle to the normal flow oilthe mercin'y that will oeuse the mercury to engage or disengage theelec= 9 trodes with o. snap action Another object oi this mvention is toprovide a mercury switch in which the circuit is com= pleted with a snapaction Toy reason of a depres sion in the envelope surface that engagesthe 5, mercury in open circuit position until there is a the electrodesand envelopes. Particles removecl gradient along the envelope floortoward the electrodes.

'Another object of the invention is to provide a mercury switch in whicha raised portion in theiiioor of the envelope causes the mercury to 5move from either end of the envelope to the other with a snap action.

A iurther object of this invention is to provide a mercury switch inwhich a. raised portion formed by an indentation in the switch 10envelope is provided in the floor of the envelope whereby the mercurycompletes two electrical circuits almostlsimultaneously with a snap actlon, holds the mercury in a position completing the second electricalcircuit after the first is broken and finally breaks the second circuitwith a shop action.

@ther objects will be app rent when reference is had to thespecification and to the drawings, in which:

Home l is a vertical sectional view taken longitudinally of the switchembodying my in ventlon and shown in open circuit position;

Flcnire S: is a vertical sectional view with a part broken away, alsoshown in open circuit position but tipped somewhat away from theposition shown in e l;

Figure 33 o vertical sectional view of the switch shown in closeclcircuit position;

Figure i is or horizontal sectional view of the switchono heinu shown ina position corresponcline to Figure 2;

is s verticol sectional view or u sec onol emhocliment oi the inventionhaving elec= trodes ior two circuits and. shown in open circuit 35position;

l lmne o is verticol sectional view oi. the mri-tch shown ho Figures,still in open circuit pc= sitlon "out tro es so the electrode end ol theenvelope is sllchtly lower than the other 4o encl;

Figure l is o verticcl sectional view showing the switch in closeolcircuit position;

is is a verticol sectional view showing the switch of Figure 5 in theposition in which one oi the circuits h closed and the other is open;onol Figure 9 is a horlzontol' sectional view of the switch and shown inu position corresponding to Floors 5.

line m w w of the invention is shown in Figures l. through t anal inthese figures lllre reierence characters refer to like parts. In thisemment oi the invention, the switch is sup- M ported by a mechanism thattips it one way or the other about its horizontal position but as thatmechanism comprises no part of the invention it is not shown. The switchis generally designated at [0 and comprises a glass switch envelope orcontainer cylindrical in form, the longitudinal axis of which isrepresented by the line H. The envelope is hermetically sealed, theprocess of sealing the envelope resulting in a sealing-oil tip H whichforms an indentation or depression I3 within the envelope. As will benoted from the drawings, the sealing-off tip I! is located on the lowerside of the switch envelope. In the other end of the envelope H! aresealed a pair of electrodes II and ii. For a purpose to be hereinafterset forth, electrode I5 is made of a metal that will amalgamateslightly. Flexible lead wires l6 and I6 are suitably secured to theouter ends of electrodes H and 15. Mercury l'l serves to complete theelectrical circuit between electrodes ll and is when moved to that endof the envelope.

The operation of the switch in its illustrative embodiment will now bedescribed by referring to Figures 1 through 4. In Figure 1, the switchis in open circuit position due to the electrode end of the envelopebeing higher than the end in which the sealing-off tip I! forming thedepression I3 is located. The axis ll of the tube is shown tippedcounter-clockwise somewhat from the line H representing the horizontal.The mercury I1 is in one body with a part lying in depression l3. Inorder to close the electrical circuit, it is necessary to tip theenvelope l0 clockwise so that the mercury will flow to the electrode endof the switch. As the envelope is tipped clockwise from the positionshown in Figure i, it will reach the position shown in Figures 2 and 4in which the axis ll of the envelope i0 is shown rotated very slightlyin a clockwise direction from the line H representing the horizontal.The mercury is still in one piece but the main body of it has moved downthe tube somewhat. Although the force of gravity is here tending to movethe mercury into engagement with electrodes l4 and Hi, the mercury isrestrained from so moving by its surface tension. Part of the mercurylies in depression I! and is held there partly by its weight, partly bya vacuum being formed beneath it and partly by its adhesion to theenvelope wail forming the depression. The

tendency of this small portion of the mercury to remain in thedepression is strong enough so that the surface tension of the mercurytending to move toward the other end of the envelope is not great enoughto dislodge it. As the envelope is tipped clockwise from the positionshown in Figures 2 and 4, the force tending to move the main body ofmercury into engagement with the electrodes becomes greater andeventually a point will be reached where the surface tension tending tohold the mercury in one piece is overcome and the mercury separates intotwo parts, one part Ila flowing downthe envelope to make contact withelectrodes l4 ,and I5, and the other part "b remaining lodged indepression ll, as shown in Figure 3.

It should be pointed out that the parts of the switch are soproportioned that at the instant the mercury separates into two pieces,the mercury is still a substantial distance away from the electrodes. Atthis instant also the tube is tipped to a position in which there is asubstantial gradient toward the electrodes. Thus, when the mercury isreleased, it will immediately commence to gain speed and will be movingquite rapidly at the time it engages the electrodes. It is apparent,therefore, that the action of this switch is such that no matter howslowly the envelope is actuated, it is impossible for the mercury tomove slowly into engagement with the electrodes and,

therefore, arcing is reduced to a minimum.

The embodiment of the invention shown in Figures 1 through 4 obtains asnap action break by forming the electrode that is first to bedisengaged by the mercury of a metal that will amalgamate slightly. Asthe mercury flb moves away from electrode IE, it adheres to theelectrode until the main body of mercury is away from the electrode andonly a small arm of mercury bridges the gap between the main body ofmercury and the electrode. On further movement of the mercury away fromthe'electrode, contact will be broken suddenly and there will be littletime for an arc to form. Since the mercury adheres to the electrodeuntil there is a gradient toward the other end of the tube, oncereleased it moves rapidly away from the electrodes.

It should be noted that while the seal-oil tip of the glass envelope isconveniently used to provide a depression in the lower surface of theenvelope, the depression may also be formed in any other suitable manneras by indenting the envelope from the insidefas would be done if theenvelope were made of metal.

Another embodiment of the invention is shown in Figures 5 through 9wherein like reference characters represent like parts. Figure 5 shows amercury tube 30 substantially cylindrical in shape and having an axisrepresented by the line 31 The tube is made of glass and is hermeticallysealed in the conventional manner at 32. In the lower side of the tubeand approximately at the center of its length, the tube wall is indentedinwardly as at 33. Indenting the tube from the outside forms a raisedportion 34 upon the inside of the tube. In one end of the tube,electrodes 35, 36 and 31 extend inwardly and have their ends bentdownwardly in such a manner that their extremities lie substantially ina line parallel to the axis SI and slightly above the bottom of thetube. These electrodes are suitably sealed in the envelope as shown at42 in Figure 9. The outer extremities of the electrodes have attached tothem flexible lead wires 38, 39 and 40.

Figure 9 shows the mercury in the position in which it is alsoillustrated in Figure 5. The shape of the raised portion 34 as viewedfrom above is here illustrated as is also the position of theelectrodes. A globule of mercury ll lies within the switch envelope andflows from one end of the tube to the other, depending upon which end isthe lower. In traveling from one end of the tube to the other, themercury must pass over the raised portion 34.

The sequence of operation of the switch is shown in Figures 5 through 8,in which line H represents the horizontal in each case. In Figure 5, theelectrode end of the switch is raised considerably above line H and themercury II is in the opposite end of the switch envelope so that theswitch is in open circuit position. As the electrode end of the switchis lowered to a point only slightly below line H, the globule of mercurymoves up to the raised portion 34, as shown in Figure 6. The tube hasnot yet been tipped sufficiently, however, to cause the mercury to flowover the raised portion ll. Mercury possesses a very high degree ofcohesion and although the level of the globule of mercury ll is abovethe top of the raised portion 34, the portion of the mercury below ahorizontal line through the top of 34 holds it in this position.

Lowering the electrode end of the switch envelope still further willeventually overcome the tendency of the mercury to remain held by theraised portion 34 and the mercury 4| will move as a unit over raisedportion 34, flow quickly down the bottom of the envelope and engage theelectrodes 35, 36 and 31 almost simultaneously. This position of theenvelope and mercury is shown in Figure 7. If now the electrode end ofthe switch is elevated to a position slightly above line H, the mercury,although tending to flow toward the other end of the envelope, willagain be engaged by the raised portion 34 as shown in Figure 8. Theamount oi mercury and the relative position of electrode 3'! and raisedportion 34 is such that while the mercury 4| is still in engagement withelectrodes 35 and 36 it has disengaged electrode 31. Thus, there is arange of positions of the envelope from a position in which theelectrode end is very slightly above line H to the position in whichmercury ti will flow over the raised portion 34 in which the electricalcircuit controlled by electrode all is open but in which the circuitcontrolled by electrodes 35 and 36 remains closed. If the electrode endof the envelope is raised beyond the position shown in Figure 8, theposition of the elements of the switch again returns to the open circuitposition shown in Figure 5.

While the raised portion 34 has been described as formed by indentation33 on the outside of the envelope, it could also he provided by othermeans as for instance by an insert placed within the tube or by makingthe tube wall of increased thickness at that point.

By omitting electrode 371 it is apparent that a switch controlling asingle circuit and in which contact is Tooth made and broken with a snapI action would be provided.

From the above it is seen that a new and novel snap action mercuryswitch is obtained wherein the circuit controlled by the switch is madeand hroken with a snap action. in one modification the breaking of thecircuit with a snap action iscaused by the same means which causes snapaction making of the circuit, while in the other modification thecircuit may be broken with a snap action "by a separate means. inaddition, provision is made for sequentially breaking a plurality ofcircuits.

Although for purposes 01 illustration two modirlcations oi thisinvention have been described, other :iorms thereof may become apparentto those skilled in the art upon reference to this specification andtherefore this invention is to he limited only by the scope oi theappended claims and prior claim as my invention: I

1. in an electrical switching mechanism, in combination, a tiltablecontainer, electrodes can tending into the container, a loody oiltluidcon ducting medium having relatively high surfaces tensioncharacteristics movable in the container upon tiltnig thereof to bridgethe electrodes for making and breaking an electric circuit, and adepression in the bottom of the container formed solely by the seal offtip and being of such a depththat it continuously retains a portion ofsaid fluiciacting in conjunction with the surface tension of the fluidfor holding the fluid in one end of the container until the container istilted to a position in which there is a suflicient gradient breaking anelectric circuit, and a depression in the bottom of the second end ofthe container formed solely by the seal-oil tip and being of such adepth that it continuously retains a portion of the fluid acting inconjunction with the surface tension of the fluid for holding the fluidin the second end of the container until the container is tilted to aposition in which there is a suiiicient gradient toward the first .endof the container to overcome the surface tension of the fluid whereupona portion of the fluid is released and moves rapidly to the flrst end ofthe container to bridge rapidly the electrodes for completing thecircuit with a snap action.

3. In. an electrical switching mechanism, in combination, a movablecontainer, electrodes extending into said container, 9. fluid conductingmedium movable in said container to bridge said electrodes, and adepression in the lower side of said container comprising the seal-offtip thereof to control the movement of said fluid conducting medium saiddepression being of 'such a depth as to continuously retain a portion ofthe fluid conducting medium.

the body of conducting fluid acting in conjunc tion with the surfacetension of the fluid asithe container tilted in the second direction toallow the fluid to unbridge certain of the electrodes for opening atleast one circuit Tout holding the fluid in contact with the remainingelec trodes until the container is tilted to a position in which thereis a substantial gradient away from the electrode end of the containerwhereupon the fluid moves away from the electrode end or -the containerto unbridge the remaining electrodes.

5. an electrical switch mechanism, in cornhination, an elongatedtiitahle container having first and second ends, electrodes in the firstend or the container, a body of fluid conducting Hid dium havingrelatively high surface tension char= acteristics movable from one endof the container to the other upon tilting thereof to bridge andunbridge the electrodes for making and breaking an electric circuit, anda depression in the bottom oi the second end oi the container formedsolely by the seal-on tip and being of such a depth that it continuouslyretains a portion of said fluid act ing in conjunction with the surfacetension oi, the

fluid. for holding the fluid in the second end oi the body or fluid inengagement therewith in the first end of the container until thecontainer is tilted to a position in which there is a substantialgradient toward the second end of the container whereupon the fluidmoves rapidly to the second end of the container to unbridge rapidly theelectrodes Ior breaking the circuit with a snap action.

6. In an electrical switching mechanism, in combination, an elongatedtiltable container, a plurality of electrodes extending into one end ofthe container ifor controlling a plurality of circuits, a body ofmercury movable in the container to bridge and unbridge the electrodesas the container is tilted, and means acting in conjunction with thesurface tension of the mercury to cause the mercury to bridge all theelectrodes substantially simultaneously to complete all the circuitsregardless of how slowly the container is tilted from circuit open tocircuit closed positions and to cause the mercury to unbridge theelectrodes sequentially to break the circuits sequentially as thecontainer is tilted slowly from circuit closed to circuit openpositions.

7. In an electric switch, in combination, an elongated tiltablecontainer having first and second ends, a plurality of electrodes in thefirst end 01 the container for controlling a plurality of circuits, abody of fluid conducting medium movable in the container to bridge andunbridge the electrodes when the container is tilted, and means withinthe container for holding the fluid conducting medium in the second endof the container until there is a substantial gradient toward the firstend or the container whereupon the fluid moves rapidly to the first endof the container to bridge all the electrodes for completing all thecircuits and for holding the fluid in a. position in which certain ofthe electrodes are bridged and certain of the electrodes are unbridgedfor breaking certain of the circuits when the container is tilted awayfrom the position in which all the electrodes are bridged to a positionin which there is a slight gradient toward the second end of thecontainer.

8. In an electrical switching mechanism, in combination, an elongatedtiltable container having first and second ends, a plurality ofelectrodes extending into the first end of the container for controllinga plurality oi! circuits, 9. body of fluid conducting medium havingrelatively high surface tension characteristics movable in the containerto bridge and unbridge the electrodes as the container is tilted infirst and second directions respectively, and an obstruction in the bottom 01' the container between the above mentioned electrodes and thesecond end of the container of such a height as to act in conjunctionwith the surface tension of the fluid as the container is tilted in thesecond direction td'allow' the fluid to unbridge certain of theelectrodes for opening at least one circuit but holding the fluid incontact with the remaining electrodes until the container is tilted to aposition in which there is a substantial gradient away from theelectrode and of the container whereupon the fluid moves away from theelectrode end 0! the container to unbridge the remaining electrodes andopen the remaining circuits.

9. In an electrical switching mechanism, in combination, an elongatedtiltable container having first and second ends, a plurality oi!electrodes extending into the first end or the container for controllinga plurality of circuits, 9. body of fluid conducting medium havingrelatively high surface tension characteristics movable in the containerto bridge and unbridge the electrodes as the container is tilted infirst and second directions respectively, and an obstruction in thebottom 01 the container between the above mentioned electrodes and thesecond end of the con tainer of such a height as to act in conjunctionwith the surface tension of the fluid for holding the fluid in one endor the container until the container is tilted in the first direction toa position in which there is a substantial gradient toward the electrodeend 01 the container whereupon the fluid moves rapidly to the electrodeend 01' the container to bridge rapidly all of the electrodes, saidobstruction also acting in conjunction with the surface tension or thefluid as the container is tilted in the second direction to allow thefluid to unbridge certain of the electrodes but holding the fluid incontact with the remaining electrodes until the container is tilted inthe second direction to a position in which there is a substantialgradient away from the electrode end of the container whereupon thefluid moves rapidly away from the electrode end of the container tounbridge rapidly the remaining electrodes and open the remainingcircuits.

u 10. In an electrical switching mechanism, in

combination, an elongated tiltable container having first and secondends, at least three electrodes for controlling at least two circuitsextending into the first end or the container, 8. body of mercurymovable in the container to bridge and unbridge the electrodes as thecontainer is tilted in first and second directions respectively, and anobstruction in the bottom of the container between the above mentionedelectrodes and the second end or the container of such a height as toallow the mercury to unbridge certain of the electrodes for opening atleast one circuit as the container is tilted in the second direction butholding the mercury in contact with the remaining electrodes until thecontainer is tilted to a position in which there is a substantialgradient away from the first end of the container whereupon the mer curywill move away from the first end of the container to unbridge theremaining electrodes and open the remaining circuits.

11. In an electrical switching mechanism, in combination, an elongatedtiltable container having first and second ends, at least threeelectrodes for controlling at least two circuits extending into thefirst end of the container, a body oi mercury movable in the containerto bridge and unbridge the electrodes as the container is tilted infirst and second directions respectively, and an obstruction in thebottom of the container between the above mentioned electrodes and thesecond end or the container oi. such a height as to hold the 'mercury inthe second end oi the container until the container is tilted to aposition in which there is a substantial gradient toward the first endor the container whereupon the mercury moves rapidly to the first endoi. the container to bridge rapidly all the electrodes, said obstructionalso acting on the mercury to allow the mercury to unbrldge certain ofthe electrodes for opening at least one circuit as the container istilted in the second direction but holding the mercury in contact withthe remaining electrodes until the con-.

tainer is tilted to a position in which there is a. substantial gradientaway from the first end of the container whereupon the mercury will movemercury, electrodes, and a well in said envelope, 5

a part of said well constituting a sealing of! tip HAROLD T. OLSON.

